Shot shell wad



Patented Apr. 9, 1946 UNITED STATES .PATZEI N T OFFICE SHOT SHELL WalterL. Finlay, Fairfield, Conn, assignor to Remington Arms Company, ='Inc.-,Bridgepbrt, Conn., a corporation of Delaware No Drawing. Application May8, 1942, Serial 'No. 442,229

40laims.

Thisinvention relates, in general, to shot shell wads, and, particularlyto an improved material for-wads.

"An object of the invention is to provide an improved material for shotshell wads which is more economical to produce than hair felts and thelike.

A further object is to provide a moldable material for wads containingfibers substantially free from water soluble deleterious materials. Afurther object is to provide a molded wad comprising a coherent body of\lignocellulose fibers and a suitable binder.

The invention lends itself particularly to the method o'f -moldlng wadssuch as described in the patent to Woodford 2,026,765. According to thepatented process, a water suspension is prepared of suitable wad-formingmaterials which may be an intimate mixture of fibers of varying lengthsandsurface characteristics witha granular .filler. Hair, felt, wastecotton, etc., are disclosed as suitable long fibers, and unhydrated woodpulp as a shortfiber. The filler used is-sawdust, wood flour, cork, orother granular material.

More specifically, the present inventionhas its inception inamodificationof the Woodtord proc-' ess wherein a mixture has beenused'comprising scrap cattle hair felt, mechanical wood pulp, and abonding material of such a character that it may be added as discreteparticles during the process of manufacture, be filteredout as discreteparticles during the laying or melding of the wad-forming material, andthen, or subsequently, be gelatinized or otherwise so dispersed as toacquire "adhesive properties. Among such bonding materials, starch wasfound to be particularly adapted to use in a process in which thewadforming material is laid in a fibr ous stock, the latter consistingspecifically of water containing granulated raw starch and substantially1% of scrap cattle hair felt and mechanical wood .ipulp in suspension.

The terms mechanical wood pulp or mechanical pulp will be understood tomean ungelatinized wood pulp consisting of short, chopped up fibers orfiber bundles, while the term laid, as used, means the formation of aself -sustaining, semicoherent body or mat of the solidand fibrousmaterials contained in the stock. Such a body or mat is obtained bydraining ofi the stock liquid through a screen, as commonly practiced inthe paper making industry, or preferably in the manner more fullyexplained in the above identified Woodford patent wherein -'a iportionof the stock may "be placed in "a wad mold. from which the liquid isdrained.

As the liquid is drained oif, a small percentage of the starch particlesare filtered out 'of the liquid and substantially uniformly dispersedthroughout the fibrous mat, the amount of starch filtered out beinggoverned in general by the porosity of the mat and the fibrillouscharacter of the interlocked fibers. 1

Following the laying or felting 'of the fibrous material, either in aform of a mat or molded article, sufficient heat maybe applied to thematerial to gelatinize the starch.

Although highly satisfactory shot she'll wads have been produced in theabove manner, yet these processes are relatively expensive. This isborne out by the fact that in order tola'y'downa fibrous mat or moldedwad of substantially halfinch thickness from stock of 1% fibersuspension, a relatively large volume of water and starch is required ofwhich substantially to of the starch is wasted when the stock liquid isdrained away; and {of all the ingredients used in making the wadmaterial, the starch is the most expensive. The necessity for discardingthe stock water arises from the fact that the scrap "cattle hair feltalmost invariably includes some Water soluble deleterious material andin specific instan'c'e's has been "found to contain substantiall 30% ofwater soluble dextrine. Thus it happens that by recirculation of thestock, the dextrine rapidly accumulates in the water so that it becomesgummy thereby contributing a gelatinous quality to the "felted'materialprior to the mol'd'ing'of the wad, whereby the wad-punches, such as usedin the above identified 'Wood'ford process, become dirty and clogged"and the molded wads "them selves are of inferior quality. A further"factor contributing to the 'expensiveness of this process is therelatively high cost of c'attle'hai-r.

The present invention is in the discovery that molded or felted shotshell wads may be produccd at 'considerab'ly less cost and at greaterproduction rates by using lignocellulose'fibers known as Asplund fibers.

The term Asplund'j as used in this specification, shall be understood todesignate lignocellulcse fibers obtained by the Asplund defibrillatin'gprocess which is fully described in United States Patents 2,145,851;2,008,892 and 2,047,170. These fibers are obtained from wood chips byseparating the individual fibers from the fiber bundles in relativelylong unbroken lengths, and are distinguishable over other'typesofwood'fibers in that the lignin which, with cellulose, constitutes anessential part of Wood tissue, is not dissolved out of the fiber duringthe process of defibrillating. The term Asplund shall also be understoodto designate lignocellulose fibers known in the trade as ChemicalAsplund fibers.

Previous to the Asplund lignocellulose fiber, all wood fibers have beenobtained either by mechanical or chemical processes or combinationsthereof, whereby the fibers were separated either as broken-up,relatively short lengths or in a degenerated form due to the loss of asubstantial quantity of lignin. The Asplund fibers are, however,defibrillated wood fibers having a structure closely resembling theoriginal fibers with more pliability and strength than any wood fibersheretofore made.

The Asplund fibers are particularly adapted to wad materials in that therelatively long unbroken length of the individual fiber is closeto idealfor felted or molded wad processes. These fibers are also substantiallyfree from water soluble materials and hence do not gum up the stock,and, consequently, the stock water remains substantially clean afterlaying or molding a wad and may be recirculated for subsequent laying ormolding processes thus preserving in suspension relatively largequantities of the costly granulated starch.

It has likewise been found that the surface of the Asplund fiber issubstantially smooth. This characteristic is of considerable importancein the commercial production of wads since the rate,

of production, in large measure, will be determined by the rate ofdraining of the stock which relatively thick fibril fuzz, then a matlaid down 7 from such stock would be so slow draining as to preclude theuse of such fibers. On the other hand, a mat formed from substantiallysmooth fibers would normally havefree draining characteristics. asundesirable as excessively slow drainage, since, in the former case,there will be substantially no filtering of starch particles by thematted fibers. However, the drainage characteristics of stock comprisingsmooth fibers may be controlled to give an optimum rate of drainageattended by proper dispersion of starch throughout the laid mat.

One satisfactory method of forming wad materials from an Asplund fiberstock is to use Asplund fibers which have been partially fibrillatedeither by a mechanical or chemical process or the combination thereof sothat the naturally smooth surface of the fibers will have fibrils formedthereon in an amount commensurate with the optimum drainage andfiltering requirements. Thus, when the Asplund stock is drained, starchparticles are impeded by the interlaced fibrils and prevented fromescaping with the stock water and are filtered out substantiallyuniformly throughout the fibrous mat.

Inasmuch as the Asplund fibers are normally smooth surfaced, the rate ofdrainage of the stock and the amount of filtered starch in the mat willbe substantially proportional to the degree of fibrillation of thefibers which factor may be varied to accord with individualrequirements.

' A specific example of the use of Asplund fibers for making shot shellwads is as follows:

A stock of a concentration of about 1% is prepared from about 60 partsof partially fibrillated Excessively free drainage is, of course, 7

Asplund fibers and 40 parts of a bonding agent, for example, rawgranular starch. The stock is beaten to secure uniform dispersion anddistribution, but not hydration of the fibrous materials. The preparedstock is then delivered to the laying or molding apparatus which, in thelatter case, may be of the form described in the abovementioned patentto Woodford. .Of the 40 parts of bonding agent in suspension in thestock, about 8 parts are filtered out into the laid material by theinterlaced fiber fibrils while the remainder is carried away in thestock water.

However, since the Asplund fibers contain no water soluble materials,the stock water is clean and free from any deleterious substances, and,therefore, may be continuously recirculated for successive mat layings'or moldings with the addition of only that quantity of starchsufllcient to secure the initial concentration.

The wads leaving the molding machine may contain substantial quantitiesof water and accordingly they are then dried by heat, the starch beingcolloidally dispersed in situ in the wadmaterial or molded wad duringthis heat treatment.

While the above method discloses the use of Asplund fibers which havebeen fibrillated so as to accomplish the proper drainage and filteringnecessary to produce wad mats or molded wads, it is also possible to usevarious mixtures of the substantially smooth Asplund fiber and a fiberor fibers having the necessary fibrillous character.

Fibers having fibrils and sufilciently economical for carrying out thepresent invention may include such materials as mechanical wood pulp,sulphite screenings, and kraft.

A specific example of the practice of the invention using a mixture ofsmooth Asplund fibers and fibrillous fibers is as follows:

A stock of a concentration about 1% is prepared from substantially 40parts of sulphite screenings and 10 parts mechanical pulp and beaten tosecure even dispersion but not hydration of the fibrous materials. Tothis stock is added about 30 parts of smooth Asplund fibers, 10 parts ofwood flour and about 60 parts of the bonding agent. The stock is againbeaten to secure uniform dispersion and distribution. The molded wad orfelted wad material is then formed from this prepared stock in themanner already describedywith only about 10 of the 60 parts of bondingagent being retained in the molded wad.

Other stocks adapted to the practice of the invention as abovedescribed, may have substantially the following compositions, aftermolding:

55 parts Asplund fibers;

'35 parts mechanical wood pulp;

Although starch has been specified as a suitable bonding agent, it willbe understood that other materials may be used which are substantiallyinsoluble in neutral water but which, in the presence of alkalies, formcolloidal dispersions. ples of such materials are the salts formed bythe Examreaction of casein and alkalies, and cellulose glycolic acid,and its salts, particularly the alkali metal salts of which sodium saltis typical. These agents may be added to the stock in the same manner asstarch and remain as separate, substantially solid particles in thestock during the laying of the felted or molded wad. However, upontreatment with an alkali such as ammonia, sodium hydroxide, potassiumhydroxide, lithium hydroxide, dimethylamine, trlmethylamine or other lowboiling point amines, they are colloidally dispersed. The alkali may beapplied to the felted material as a dilute solution either during orsubsequent to the laying of the wad forming body.

While the above described stock compositions have been found in practiceto produce relatively inexpensive wad material or molded wads of goodquality, this invention is not to be considered as limited to thespecific materials and operations herein described by way ofillustration, since it extends to all equivalent materials and processesfalling within the scope of the appended claims, which are to be broadlyconstrued.

What is claimed is:

1. A shot shell wad comprising a resilient cylindrical felted structurecoherent under shot shell firing conditions and consisting essentiallyof fibrillated Asplund fibers interlaced to provide binder segregatinginterstices and segregated portions of a starch paste binder adheringessentially to the interlaced fibers only of the respective intersticesthroughout said structure to provide a permeable structure and to holdtogether said interlaced fibers.

2. A shot shell wad comprising a resilient cylindrical felted structurecoherent under shot shell firing conditions and consisting essentiallyof Asplund fibers and fibrillated kraft, said fibers and fibrillatedkraft being interlaced to provide binder segregating interstices andsegregated portions of a starch paste binder adhering essentially to theinterlaced fibers and kraft only of the respective intersticesthroughout said structure to provide a permeable structure, said Asplundfibers and fibrillated kraft being held together by the combined actionof said interlaced fibers and kraft and the segregated portions of saidstarch binder.

3. A shot shell wad comprising a resilient individually molded structurecoherent under shot shell firing conditions and consisting essentiallyof fibrillated Asplund fibers interlaced and disposed in a multiplicityof randomly oriented planes throughout said structure to forminterstices therein, and a starch paste binder only partially fillingsaid interstices throughout said structure to provide a permeablestructure and to hold together said interlaced fibers.

4. A shot shell wad comprising a resilient individually molded structurecoherent under shot shell firing conditions and consisting essentiallyof Asplund fibers and fibrillated kraft interlaced and disposed in amultiplicity of randomly oriented planes throughout said structure toform interstices therein and a starch paste binder only partiallyfilling said interstices throughout said structure to provide apermeable structure, said Asplund fibers and fibrillated kraft beingheld together by the combined action of said interlaced fibers and kraftand said binder.

. WALTER. L. FINLAY.

